My old fan was pretty weak. Just a small fan bought from big box store ducted to the outside.

My new vent fan which is part of the tubular skylight is behind the trim of the skylight. It's whisper quiet but has a much more powerful fan than my old one. It's also ducted to the outside and when it's on I can see the vent trap opening indicating that there's air movement to the outside.

I am not sure if the fan is evacuating the moisture after a shower. And if it is, I think it may not be doing it very well. This is a SMALL bathroom. I have the door cracked open a little bit so it has some intake air. And after a shower I leave the fan on for several minutes. How long should I have to leave the vent fan on?

When I get out of the shower the mirror and the walls are wet. Showers are about 10 minutes or so.